It is known that aqueous and organic extracts of certain plants including ginger, bamboo grass, mugwort, etc. contain antimicrobially active principles. By way of illustration, Japanese Patent Kokai No. 32705/1985 discloses an antimicrobial composition containing a ginger rhizome extract as an active ingredient.
Derived from naturally-occurring sources, namely plants, such antimicrobial substances are safe and expected to find application in the field of food and cosmetic additive ingredients, among others.
Moreover, though unrelated to antimicrobial use, Japanese Patent Publication No. 8694/1986 describes a deodorant composition containing a dry distillate of tea leaf boiling between 180.degree. and 200.degree. C. at 20 mmHg, for instance.
While antimicrobial agents extracted from plants are generally more desirable than synthetic preservatives and synthetic antimicrobial agents as far as safety is concerned, they are usually less active than the synthetic substances. Moreover, because of the characteristic odor, taste and color which trace back to the source plant, a natural substance is often considered unacceptable for food or cosmetic use. Furthermore, the extraction process required is not only time-consuming but entails a complicated after-treatment.
The inventor of this invention having done an extensive exploration into antimicrobial substances occurring in plants arrived at the assumption that antimicrobial substances in situ, namely in plants, are mostly in a masked state as its functional groups intrinsic to antimicrobial activity are bound to each other to form a condensate or polymer and such condensed or polymerized substance, if extracted, would not fully deploy its antimicrobial potential. Starting from that assumption, the inventor did further research and developed this invention.
The object of this invention is to provide an antimicrobial composition of matter having high antimicrobial activity and substantially free of the characteristic odor, taste and color of the source plant.
Another object is to provide a shaped antimicrobial article either containing or carrying said substance.
It is a further object of this invention to provide a method of producing said antimicrobial composition of matter.